Petri dishes are flat, round, generally transparent dishes with a bottom and a cover that overlaps the bottom, which are widely used in biology, medicine, or chemistry. Thus, Petri dishes are used for the cultivation of microorganisms and cell cultures.
Microorganisms are introduced in situ into a nutrient medium in the bottom. Then the Petri dishes are usually incubated with the cover on the bottom and the nutrient medium on the top. In this storage, the weight of the plate rests upon the cover, wherein the seal between the cover and the dish is improved. Excess water is not formed on the nutrient medium, rather is accumulated on the cover.
During the incubation period, the growth of the cultures is frequently inspected visually. For applications in which large numbers of plates are worked with, there is a need for automation of this process. Thus, a Petri dish is removed from the incubator and/or the storage device according to a specific timetable, and a processing device, especially an analysis device, is introduced. For the inspection, the plates should be introduced into the inspection device with the culture medium down.
For transferring the Petri dishes between storage and the inspection device, a transfer device is needed. Usually this has a pivot arm that is arranged on a wall of the incubation chamber or storage device. A Petri dish is engaged by a vacuum suction device, which is arranged at the outer end of the pivot arm, and is simultaneously removed from the incubator and inverted by a 180 degree rotational movement. The vacuum suction component in the inspection device must be removed for the inspection.
A device is known from EP 2 482 079, in which only the bottom of the Petri dishes is inverted.
Other solutions are based on the Petri dishes being inverted by a transport lift within the incubator. Here there is a risk of contamination of the entire incubator due to the possibility of the loss of the plate.